1. Field of the Invention
The present invention relates to a camera and a method for adding an image or pattern to a photograph image.
2. Description of Related Art
When a picture is taken, it is sometimes desirable to add or superimpose a desired image or pattern onto the picture to achieve advertising effects or simply to make the picture more attractive or appealing. The common methods to achieve this are:
1) Post-processing of the film to add an image, words or pattern onto the final photograph.
2) Use of a digital image processing technique together with use of a digital camera or other digitizing means.
3) Shooting of an object against a background screen with a pattern preprinted or projected onto it.
4) Installation of a filter pre-printed with the desired image or pattern in the camera such that when a picture is taken, light passes through the filter whereby the pre-printed image or pattern is printed on the film. In known cameras which use this arrangement, a number of filters are provided which are pre-printed with images or patterns and can be placed inside a central rectangular recess area of the internal compartment of the camera before mounting the film.
The first two methods, which rely on post-processing, have the disadvantages of being expensive to implement and inconvenient for casual picture taking. The third and the fourth methods both use pure optical methods to achieve the desired result. The third method has the disadvantage of being location dependent and inconvenient. Although the fourth method is inexpensive and convenient to use, it has the disadvantage that the filter cannot be conveniently replaced without replacing the whole roll of film, so that patterns cannot be changed at will within one roll of film.
In the known fourth method in which a filter (or slide) bearing an image or pattern is placed inside the camera between the lens and the film the following problems arise:
1) The pattern can intermix with the background of the object to be shot. If the pattern is colored, a color of the pattern will be changed if it is mixed with the color of the object background. One solution to this problem is to partition the ambient light into one portion for illuminating the pattern and another portion for illuminating the object to be shot.
Patent application No. EP-A-0499742 describes one method of doing this. It uses an area of translucent material placed near the camera aperture allowing only white light to pass through and a dividing structure to isolate the extracted white light from the light constituting the object to be shot.
2) In the method described by patent application No. EP-A-0499742, it is necessary to enlarge the aperture of a standard camera to accommodate and illuminate the translucent material. In so doing, due to the distance travelled by the shutter plate(s), exposure time varies across the film and the photograph so produced will be subject to non-uniform exposure which is undesirable. This problem in fact also occurs in a standard camera although it is generally not noticeable; the problem however is aggravated when the aperture is enlarged.
3) Where a translucent material or other means is used to extract white light from the ambient light, due to the extra dissipation of light energy during the extraction, the intensity of light illuminating the pattern may be insufficient to produce a desirable composite picture.
If a slide (or plate) bearing an image or pattern to be superimposed is placed outside the camera, the desired effect can also be achieved. Two problems need to be resolved in this method:
1) The pattern, being placed at an unusually close position to the lens, needs to be focused properly onto the film.
2) It is necessary to provide appropriate and uniform lighting to the pattern.